Researchers from the University of Regina are studying if the drainage of wetlands is leading to more mercury being emitted into the atmosphere. The effort is the first of its kind on the prairies, particularly in Saskatchewan, where the draining of wetlands or sloughs is common agricultural practice to free up more land for crops – while the burning of coal globally has resulted in a large portion of the mercury emissions currently found in the atmosphere. “What we’re really interested in is, if you drain a wetland, does all of that methylmercury, that has basically been produced in the wetland, react and then be readmitted into the atmosphere where it would become part of that global pool and therefore then fall on other places,” research lead and professor of biology Britt Hall told CTV News. What is mercury? Mercury is recognized as a global contaminant by Health Canada and can be harmful to one’s health. As fans of Lewis Carrol’s 1865 classic “Alice in Wonderland” may know, the “Mad Hatter” character was based on a common phenomenon with hatmakers at the time, who developed chronic mercury poisoning from high exposure – as elemental mercury was used in the production of felt hats. According to Hall, mercury is emitted whenever a substance containing the element is burned – which can range from oil, to wood, to coal. Thrust into the atmosphere, the traces of mercury travel through the air before they eventually settle back down to Earth – where they can land in wetlands or lakes. Once the mercury is introduced into that environment, it interacts with bacteria and other organisms, where it can transform into organic mercury, most commonly a compound called “methylmercury.” “Methylmercury is an even more neurotoxic element, and it has properties, chemical properties, that allow it to bioaccumulate, which basically means that it sticks to our tissues, specifically proteins,” Hall explained. “We eat a lot of protein when we eat a fish. So, the older the fish, and the bigger the fish, the more mercury it has.” Methylmercury poses a larger risk, due to its ability to cross the body’s blood/brain barrier, according to Hall. “So, the methylmercury is in your blood if you eat it, and then it can go into your brain, and then it can bind into the proteins of your brain and cause those neurological issues,” she added. Effects of drainage Many of the sloughs and lakes Hall’s team studies don’t contain aquatic life – meaning the effect of eating fish containing large amounts of methylmercury is not a factor in this research. The team is more so focusing on how the mercury is transferred when drainage occurs. “So, we are interested in some of the other questions around how mercury moves in the environment and the potential consequences for the way our climate is impacting those wetland sloughs,” Hall explained. Once in the atmosphere, the mercury can stay suspended for more than a year – potentially travelling across the planet. “It can deposit anywhere. So, in Saskatchewan, we can have Saskatchewan coal being burned, but we can have mercury being deposited from China, from India, from anywhere in the world, and it’s deposited everywhere,” Hall added. Small wetlands that fill up during the winter and dry out over the summer can be a larger source of methylmercury than established lakes, according to the research. “It seems like when these ponds are recently dried, they are a greater source of mercury to the atmosphere than when they are fully dry or fully wet,” Hall explained. How the research works Hall’s team uses a piece of equipment called a “Tekran Mercury Analyzer” to measure the amount of mercury being emitted in the atmosphere from a sample of sediments. Researchers set down a container dubbed a “cake dome” which acts as a chamber. Compressed air is blown into the cake dome – which is connected to the Tekran Mercury Analyzer. The analyzer detects how much mercury is suspended in the air. From that reading, researchers are able to determine what areas of the wetland are more saturated with mercury and where there is less. “What we’re finding is that when we put our cake dome on sediments that are recently dried or very, very wet, we’re seeing about twice what we’re seeing in the atmosphere,” Hall explained. “As we move that cake dome to different spots in the wetland, as we move it to drier spots, we’re seeing less mercury coming out. So, it seems like when these ponds are recently dried, they are a greater source of mercury to the atmosphere than when they are fully dry or fully wet.” The Minamata Convention on Mercury, signed in 2013, requires Canada to keep track of how much mercury is being emitted from its landmass. Hall’s team is the only group tracking levels in the prairie region. Hall says it’s an understudied subject. “The amount of work that is being done on the emissions of mercury from wet or dry land surfaces in Canada is understudied, and it is a global concern,” she said. “So, there are other groups that are doing this work, but it is a relatively understudied part of looking at how mercury moves in the environment.” With more and more data, researchers can create a more detailed picture on how mercury is distributed into the environment – and how to stop it. “When we continue on with this work, when we figure out what controls the amount of mercury emitting, we can then model other scenarios. We can model into the past. We can model into the future,” Hall said. However, even with the preliminary findings – Hall is already quite sure of one important point. “We need to protect our wetlands,” she concluded. “We have lots of reasons to protect our wetlands – and keeping the mercury in the ground might be one of those reasons.”
